Heater core valve

[menesesjesse]

Is this available along with the arm.  I was pulling the core out and that booger was frozen.  I cut arm so I wouldn't damage the flaps and body. Am I in for a long search?  Thanks

[Tyler S]

Yes they are available. Buds Benz has a small kit including this for repair. Part #x248-002
Look at the bottom of the page for a picture of what you get
https://www.budsbenz.com/catalog/230-250-280-sl/x-heater

[RonDwyer]

Try a spray of it with Kroil, then gently work the parts off with a back & forth motion.  Never force anything, let the solvents do the work.  Be prepared to give up, go back at it tomorrow.  Chemicals are your friend. 

[menesesjesse]

Thanks all

[Benz Dr.]

I usually try to knock them inwards slightly to start some movement. Then I use a number of small washers and a screw with a nut to use it like a gear puller. Thread the screw into the tap and then use the washers and nut to slowly pull if from the housing. Go slowly and knock it back in if it appears to get stuck on the way out.

NOTE:  be careful knocking the tap into the core as it will fall in if you drive it too far.

[Jonny B]

Here is the link for the technical manual, that discusses some approaches and some tips for the heater valve
https://www.sl113.org/wiki/Electrical/Heating

[ejboyd5]

M-B Tool for heater valve core removal.   M4 thread also appears on top of spark plug if you're looking  for a quick handle to remove a core that is not firmly stuck.

[mbzse]

M-B Tool for heater valve core removal.../...

Thread is here https://www.sl113.org/forums/index.php?topic=22680.msg162294#msg162294

[RonDwyer]

I managed to extract both of mine and discovered I have a 2-piece valve.  The seal o-ring is in a brass ring that the center shaft of the valve rotates in.  There is a second square profile shaft seal ring inside this brass ring.  The classic center is stumped, Tom says he has no idea what I have in this 69 W108.  Anyone have some ideas on a 2 piece valve? 

[Jonny B]

I can't help with the 108 heater valve, but it would probably be a good idea to post a picture of what you have mentioned in the post.

[RonDwyer]

Note how the barrel is on a separate ring?  It's the inner seal that is a square profile.  Tom sent me some really skinny round ones that don't seem right.  It is a round profile and the rings in these valves all seem to have a square profile.  I put it together and it operates smoothly, hope they don't leak! 

[wwheeler]

That is an odd core for sure.

A note about O-ring fit: The groove is always wider than the O-ring. That is normal. O-rings in this situation compression set into a square shape as they age. Old O-rings are never completely round. When you place a new O-ring in the groove, it should stick out of the groove only a little bit. This is the sealing interference. As O-rings grow in section (not diameter) they have more interference. I believe this are 3mm section METRIC O-ring and would have about .35mm of interference. So not much. If it operates smoothly with some drag, you probably have the correct O-ring.

Many people make the mistake of going to the hardware store to buy O-rings for this. It is wrong for two reasons 1) Most hardware store O-rings are Imperial inch sizes and are too fat in this application. Binding will result. 2) Hardware O-rings are usually Nitrile and not the best for water/coolant exposure. They won't last as long as O-rings meant for hot water/coolant.

I hope that helps. 

[Tyler S]

I purchased this Viton Metric O-Ring kit a while back and it has been invaluable!
From the cold start solenoid, heater valve, and even the fuel pump electrical terminals.
http://ebay.com/itm/180-Piece-Metric-Viton-O-Ring-Kit-Excellent-Protection-in-High-Heat-Applications-/161265431136

[wwheeler]

Great idea and a good price! Such a good idea in fact, I just bought one.

Yes, good idea to have the metric sizes because they can be hard to find quickly. The only one automotive fluid I am aware of that is NOT compatible with Viton (DuPont's name for Fluoropolymer FKM), is DOT 3 and 4 brake fluid. I believe silicone brake fluid is OK though. For brake fluid, EPDM is usually recommended.
Fuel, water, coolant and oils are all great with Viton. Viton is very high temp rated and up to 400*F and typically lasts a very long time in automotive use. In fact, the newer brown colored front crank seals are FKM. No coincidence that these O-rings are brown also as that is usually a sign of a FKM rubber.

Makes you wonder why manufacturers don't use FKM O-rings more often. I guess every penny saved........